The ability to detect and quantify contaminants has experienced enormous progress over the last few decades. Where once we were lucky to detect contaminants at it parts per million level, today it is common to detect contaminants in parts per billion and parts per trillion level, with parts per quadrillion level on the near horizon.

The old wet chemistry methods, while still occasionally used, have been replaced by mass spectrometers and gas chromatographs. Newer instrumentation like hydride generation, inorganically coupled plasma/mass spectrometry, and gas chromatography/mass spectrometry have lead the way. New microbiological methods have been developed to rapidly detect living organisms. New DNA based methods are in development for different types of microbes.

Yet, easy detection and quantification for some contaminants remains elusive, as is the case for the protozoan Cryptosporidium. Progress continues to be rapid and analytical detection methods will continue to improve to help utilities assure the safety of drinking water.